共轴偏光瞳折轴三反射光学系统装调方法

为了实现共轴偏光瞳折轴三反射光学系统的高精度装调,提高其光学成像质量,研究了大口径非球面反射镜的微应力装配以及光学系统共基准的调校方法。采用光学定心加工实现主、次反射镜光轴基准与相应构件机械轴基准的高同轴度;采用Zygo激光干涉仪检测波像差,指导主镜、次镜以及三镜的装配过程,保证各反射镜装配组件完成后的面形精度与裸镜一致,并最终指导完成主次镜光学系统以及三反射光学系统的像质调整。此外,由于整个光学系统是偏轴使用的,推帚方向垂直于电荷耦合器件(CCD)线阵方向,采用折轴镜旋转并修切折轴镜垫圈的方法来消除由于折轴镜倾斜而引入的系统像散。实际装配结果表明:光学系统各个视场处的成像质量均达到系统装配指标,光学系统波像差均方根(RMS)值小于0.07λ,传递函数(MTF)大于0.57。

Alignment Method of Coaxial Eccentric-Pupil Three-Mirror System

In order to realize the high accuracy alignment of co-axial eccentric-pupil three-mirror system, and to improve the image quality, the micro-stress installation of large-aperture aspheric mirror and system benchmarking adjusting techniques are investigated. The optical calibration and mechanical calibration of primary mirror, secondary mirror and third mirror are unified by using optical alignment machining. The assembly of three mirrors, also the aberration adjustment of two-mirror system and three-mirror system are realized by the instruct of wavefront aberration distribution which is gained from Zygo interferometer. The pupil of coaxial three-mirror system is eccentric, and the sweeping direction is vertical with the linear charge coupled device (CCD) direction, the system astigmatism brought by the tilting of folded-axis mirror is removed by rotating the folded-axis mirror and trimming the neighboring circle. Alignment results indicate that the image quality targets of optical system′s each field-view are achieved, the root mean square (RMS) of optical system is less than 0.07λ, and the modulation transfer function (MTF) is larger than 0.57.